1. Field of the Invention
This invention relates to feed control for a log and/or tree chipper. More particularly, the invention relates to an apparatus for improving the feeding performance of the infeed system of a log and/or tree chipper without increasing the cost or complexity thereof by providing an additional feed roller under the main feed roller on the feed table of a log/tree chipper.
2. Background Art
The present state of the art in large log/tree chippers is to help assist feeding with an infeed conveyor on the feed table. The infeed conveyor is typically a series of WD style drag chains running side by side. The individual drag chains may have a small, occasional tooth welded to the side of the chain every four to eight links to assist in the movement of material. The chain runs around a head pulley and a tail pulley assembly. The head pulley is made up of a shaft with a wide sprocket welded to the shaft at every drag chain. The sprocket drives the infeed chain and the infeed chain moves the material to be fed. The lack of aggressive features means that the chain will move material laying on it as long as it does not meet restriction from other infeed features. If the material is restricted, then the chain and head pulley slip underneath the material and the upper feed roller is thereby forced to do all of the work. To solve this problem one manufacturer of this type of machine has begun to install a lower feed roller between the head pulley and the cutter drum shear bar. This lower feed roller has aggressive knives welded to the outside surface to bite into the wood like the top, main, feed roller. With this aforementioned arrangement, the wood is pinched between an upper and lower aggressive feed roller and is more likely to overcome restrictions as the wood is forced towards the cutter drum. A disadvantage is that this adds expense, complexity, and increased possibilities for failure. The additional expense is in the production of the added feed roller and the drive system for it. The additional complexity results from there being more parts required, especially in combining the drives effectively of the main feed roller and the added lower one. The increased failure points result from the use of the needed additional bearings, the drive system, also resulting in more locations for material to wrap around one of the additional shafts.
There is, therefore, a need for a method and apparatus for overcoming the aforementioned problems with prior art feed roller systems for large tree/log chippers.